The quark-antiquark pair (or dijet) production at DIS has been argued to be an important process that allowing to access the partonic structures in momentum space. Especially, when the produced jets are mostly back-to-back, the novel process can be used to as a proxy to probe the Weizsäcker-Williams (WW) gluon distribution [1]}. The WW gluon distribution, as one type of gluon TMDs, which features an intrinsic gauge link structures: either future-pointing or past-pointing gauge links in light-cone gauge and can be interpreted as the number density of gluons inside the scattered target [2]}, [3]}, [1]}. As addressed in Ref. [5]}, a nontrivial feature has been realized that these gluons can be linearly polarized even if the hadron is unpolarized, especially, if sizable, can give a large impact on physical observables, for examples, the (pseudo)scalar particle productions in hadronic collisions [6]}, [7]}, [8]}, as well as the azimuthal correlations of dijets in DIS [9]}, [1]}, [11]}, [12]}, [13]}, [14]}, [15]}, [16]}, [17]}, [18]}. In Refs. [19]}, [20]}, for dijets production in DIS, it has been shown that unpolarized WW gluon distribution associated with its partner, linearly polarized one, enter the cross section through an azimuthal modulation. Recent developments also shown that the two gluon distributions not only exist in DIS processes, but also wildly appear in other processes, such as the dijets or quark-antiquark pairs [21]}, [22]}, [23]}, photon pairs [24]}, muon pairs [12]}, quarkonium [26]}, [27]}, [28]}, [29]} productions in hadronic collisions. A particular feature is that the unpolarized WW gluon distributions are always accompanied by its linearly polarized parts through an azimuthal modulation, this suggests that these gluon distributions (especially for the linearly polarized parts) can be extracted by measuring the azimuthal observables. Another interesting feature has been pointed out that the linearly polarized WW gluon distribution will tend to its saturated bound at large transverse momenta, while is suppressed at small transverse momenta region [19]}, [20]}, which was then further confirmed by numerical calculations in Refs. [17]}, [18]}, for recent review please see Ref. [34]} and therein. Up to now, the two gluon distributions, apart from the positive bound of linearly polarized part, are still little known experimentally, therefore, to precisely extract and quantitatively understand the behaviors of the two gluon distributions at high energy limit, which allows us in depth understanding the transverse tomography of proton and nucleus, as well as the underlying dynamics at high energy scatterings.
